DeDot

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Abstract
Author thejam79 / minamina
Version v0.0.02
Download DeDot_YV12_0002.zip
Category Rainbow & Dot Crawl Removal
License GPLv2
Discussion

Contents

Description

Spatial and temporal plugin to reduce cross-luminance (dot crawl) and cross-color (rainbows). The official name of this plugin is DeDot_YV12 and is based on DeDot v0.3 by thejam79.

Requirements

  • MMX2 compatible CPU


Syntax and Parameters

DeDot (clip, int "luma2d", int "lumaT", int "chromaT1", int "chromaT2")


clip   =
Input clip.


int  luma2d = 20
Spatial luma threshold. Lower values consider more pixels as cross-luminance.


int  lumaT = 20
Tolerance for temporal variation in the luma channel (Y). Higher values consider more pixels as cross-luminance.


int  chromaT1 = 15
Tolerance for temporal variation in the chroma channels (U,V). Higher values consider more pixels as cross-color.


int  chromaT2 = 5
Temporal chroma threshold. Lower values consider more pixels as cross-color.


Examples

DeDot with all default values:

MPEG2Source("DotCrawl.d2v")
DeDot(luma2d=20, lumaT=20, chromaT1=15, chromaT2=5) 


Reduce dot crawl only:

  • Adjust luma2d and lumaT accordingly.
MPEG2Source("DotCrawl.d2v")
DeDot(luma2d=20, lumaT=20, chromaT1=0, chromaT2=255) 


Reduce rainbows only:

  • Adjust chromaT1 and chromaT2 accordingly.
MPEG2Source("Rainbows.d2v")
DeDot(luma2d=255, lumaT=0, chromaT1=15, chromaT2=5) 


How it works

Written by tritical

I'll give a quick explanation of how the parameters are used in relation to pixel values (this is all taken simply from reading the source code).
Its operation is quite simple, which is why it is very fast and is able to be written completely in MMX.


For filtering luma (dot crawl) it uses luma2d and lumaT... Consider 'e' to be the current pixel and a,b,c,d,f,g,h,i to be its spatial neighbors in the current frame:

a b c
d e f
g h i

DeDot first uses the following two tests:

abs(b+h-2*e) > luma2d
abs(d+f-2*e) > luma2d

If either of those conditions is met it goes on and tests the following conditions else it drops out w/o doing any filtering on that luma pixel.
For the next tests consider pixel 'c' to be the pixel in the current frame and a,b,d,e to be its temporal neighbors in adjacent frames:

a b c d e
abs(c-a) <= lumaT
abs(c-e) <= lumaT
abs(b-d) <= lumaT

If all three of those conditions are met it decides that the pixel needs to be filtered and it either averages the current pixel 'c' with 'b' or 'd' based on whichever one is closer to the value of 'c'.


Chroma filtering (rainbow removal) works in the following way. First it tests the following conditions... Again assume 'c' is from the current frame and a,b,d,e are the temporal neighbors:

a b c d e
abs(c-a) <= chromaT1
abs(c-e) <= chromaT1
abs(b-d) <= chromaT1
abs(c-b) > chromaT2
abs(c-d) > chromaT2

If all five of those conditions are met then it does filtering on the pixel. For the filtering it either averages the current pixel 'c' with 'b' or 'd' based on whichever one is closer to the value of 'c'.

Hope that helps explain the parameters a little bit better.

Changelog

 v0.0.01:
     - Initial release


External Links

  • Doom9 Forum - DeDot discussion and English translation by niiyan.
  • Doom9 Forum - DeDot discussion and English translation by helix. In the last post, tritical explains how DeDot works.
  • Doom9 Forum - DeDot discussion about correct usage, English translation, and some history of DeDot by niiyan.
  • Scintilla's Guide - English documentation by Scintilla.




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